1. Priority
Priority is claimed to German Patent Application No. DE 102007014789.0-33, filed Mar. 28, 2007, the disclosure of which is incorporated herein by reference in its entirety.
2. Field of the Invention
The invention relates to an arrangement of at least one power semiconductor module and a printed circuit board as well as a power semiconductor module.
3. Background
Arrangements between semiconductor modules and printed circuit boards can be found in various areas of electrical engineering, for example in a drive control device for an electric motor. The circuit arrangement of such a drive control device comprises various function blocks, for example rectifiers, inverters and braking controllers. These function blocks are formed by power semiconductor components and/or power semiconductor modules, the latter being able to contain all the necessary power semiconductors and in addition further components, for example components for monitoring the power semiconductors, which can comprise for example temperature and/or current sensors. The power semiconductor components and/or power semiconductor modules are usually disposed on a printed circuit board and are connected by screwing, plugging or soldering to the latter.
There are known from EP 0 513 410 B1 and DE 196 46 396 C2 power semiconductor modules which in each case comprise an electrically insulating substrate, on which a circuit arrangement with power semiconductor components is disposed. The substrate forms the bottom of a plastic housing which surrounds the circuit arrangement. The electrical power terminals of the modules making contact with the circuit arrangement extend through the housing to the exterior. The housing is filled with casting compound in order to protect the circuit arrangement. Fastening points on the housing are used for screwing the module to a heat sink. Various modules are connected to one another by means of conductor bars in order to create a more extensive circuit. Such a bar connection is made in a second plane at a distance from the heat sink, in order to ensure sufficient air gaps and creepage distances for the purpose of electrical insulation. Following in the same plane or above the latter are wiring devices and an electronic printed circuit board, for example for controlling the power semiconductor components or for their monitoring.
This known design of power semiconductor components and/or power semiconductor modules including protection devices and control electronics requires a high outlay on materials and on numerous intermediate steps and screwing, soldering and assembly steps in production. Furthermore, the heat generation caused by the power loss during the operation of the power semiconductor modules is usually concentrated on relatively small areas. This heat generation can reduce the power of the overall system and the reliability of the power semiconductor modules. A fairly large outlay on the cooling of these power semiconductor modules is therefore required.
Alternatively, so-called discrete power semiconductor components are for example used in suitable built-on accessories. As a rule, these represent individual functions in one housing in each case. Power semiconductors are soldered here directly onto a metallic carrier plate and enclosed for protection. These components can be distributed spatially in the electronic power arrangement, so that a better distribution of the heat is achieved in the heat sink and, in that case, the outlay on implementing adequate cooling can be reduced. They are characterised by a mechanically robust design and, as a result of large unit quantities, are available at low cost as elements for the most varied circuit functions in standardised designs. The drawback is that the carrier plate, which serves to dissipate heat, is not electrically insulated from the power semiconductor and thus carries an electrical potential. For the assembly of such discrete power semiconductor components on a common heat sink, therefore, additional insulation is required which, however, has a markedly unfavourable effect on the heat discharge to the heat sink. As a rule, these components are fastened on the heat sink by means of a screw or clamp assembly, which requires additional assembly parts, such as small insulation plates and/or heat conducting materials, screws, assembly clamps and corresponding assembly outlay. Furthermore, it is as a rule necessary to accept limitations with regard to the soldering process. On account of the lack of insulation, components are used which in their dimensions and other properties are comparable with the described components, but with which a solid metallic carrier plate is not used, but rather use is made of a ceramic base plate metal-coated on both sides. Such components are described for example in DE 196 25 240 B4 and U.S. Pat. No. 6,404,065. Nonetheless, additional assembly parts and special assembly steps are also required here for the assembly on the heat sink and where necessary, for the soldering into the printed circuit board.
The terminal combs of components used for the electrical contracting are as a rule led out flat towards the sides. For many applications, therefore, there is the problem of maintaining the air gaps and creepage distances between the terminals with the various voltage potentials on the one hand and between the terminals and the metal-coated carrier plate or heat sink in the application on the other hand.
WO94/29901 describes an arrangement which comprises a printed circuit board with strip conductors, semiconductor components disposed on the printed circuit board and making contact with the strip conductors and a heat sink. The printed circuit board is screwed to one leg of the T-shaped heat sink. Disposed between the heat sink and the printed circuit board is a spring element, which comprises two lateral spring tongues which are intended to press the semiconductors against the heat sink as a result of their bending and pre-tensioning.
There is known from U.S. Pat. No. 6,035,523 A an arrangement comprising a printed circuit board, a semiconductor module and a heat sink, wherein a thermoplastic material is introduced between the semiconductor component and the printed circuit board, said thermoplastic material being intended to carry the semiconductor components.